<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>文档标题</title>
    <style>
        .father{
            border: 1px solid #f00;
             overflow: hidden;  /*清除浮点 */
        }
        .son{
            width: 100px;
            height: 100px;
            background-color: pink;
            border:1px solid deepskyblue;
            float: left;
        }
    </style>
</head>
<body>
    <div class="father">
        <div class="son"></div>
        <div class="son"></div>
        <div class="son"></div>
    </div>
    1123
</body>
</html>